• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Misfire or broken parts 6.5 diesel

B

Bulldog04!

New Member
Messages
4
Reaction score
8
I’m sure it’s been asked or talked about. I have a 1994 6.5 turbo that was a good running driving power train doner put it in another rig when it was out put new bearings in the bottom end and put together other pickup. Started it and it has a heck of a vibration kinda like miss fire but vibrates the dash and all I’ve cracked 6 out of 8 injectors and have fuel. Pmd is relocated etc. like I said it was a good running power train outside of getting new bearings. I’m at a loss what to look for the other two injectors are right behind the turbo is why I haven’t bled them but any help would be great
 
You swapped engine and trans together? Sounds like it could be a balance issue. First crack each injector loose one at a time while the engine is running. Be careful of high pressure spray as it can inject into your hand and cause a very bad day. If you find one that doesn't make any difference if it's open or not then that cylinder is one to check closely.
 
Verify the harmonic balancer is in good condition, they are engine killers and like to snap crankshafts. also the flexplate too. was there anything pulled apart or loosened on the engine during the transplant like the IP or timing components. These engines are externally balanced.

if the HB is good and timing wasn't messed with, then I would install a clear hose on the IP return to check for air in the fuel. also make sure you have good pressure from the lift pump. check all 8 injectors for fuel like said above.

did you keep the same ECM with the transplant? maybe there is something with that too depending on what the engine came out of.
 
MrMarty51 said:
What flywheel/flex plate did You install ?
If it was not specific to a 6.2 or 6.5 then it will be out of balance.
But IDK if a gasser unit would mate to a 6.5 diesel.
Click to expand...
Gasser flywheel has wrong teeth count & will not function with the starter.

I am leaning to air in the fuel system.
Follow the above for it. Also, out the front/top of the ip (injection pump) is a 1/4” diameter fuel hose about 5 or 6” long, in an upside down “U” shape. Replace that hose with clear tubing. If in a hurry, hardware stores sell clear pvc tube by the foot. Buy screw type hose clamps for it as the factory spring style won’t work because the clear tube is thicker material. If you can wait a day or two- buy some from Fuel-line.com (has to have the dash in name) because that is actually fuel line and will withstand the ethanol that is in all our diesel fuel nowdays and will last many years. The hardware stores sell clear stuff lasts a few years and needs replacing.
The purpose is to see contamination in the fuel, see that fuel is flowing through, and that there is no air intrusion occurring. A small trapped bb of air is ok. Any flowing bubbles indicates a leak somewhere that is sucking air in.
Leave the clear line in permanently. Any time there is any hiccup, a simple glance tells a lot- it is the first step in GM’s diagnostic flow chart.

If you can, make a video- post it and we can see more of what’s happening. If you can’t post it here- YouTube or similar then post a link.


Once this is solved- take time to learn more here, we can save you thousands of dollars and tons of headaches. There is more to help the fuel system and other things but for now, one step at a time.
 
Bulldog04! said:
I’m sure it’s been asked or talked about. I have a 1994 6.5 turbo that was a good running driving power train doner put it in another rig when it was out put new bearings in the bottom end and put together other pickup. Started it and it has a heck of a vibration kinda like miss fire but vibrates the dash and all I’ve cracked 6 out of 8 injectors and have fuel. Pmd is relocated etc. like I said it was a good running power train outside of getting new bearings. I’m at a loss what to look for the other two injectors are right behind the turbo is why I haven’t bled them but any help would be great
Click to expand...
Ive owned these since 1984...and still own a 98 K2500 Suburban and a 1994 K1500 Blazer Z71 with 6.5. Im no authority own these engines. I have learned a little. They are simple and dependable. I would look for the simple problem. In your case 1. Replace PCM AND check connections. 2. Check for a stuck injector....any bad fuel you know of? I bought a new engine years ago because to me and a diesel shop it sounded like a rod was loose...or worse. It was a stuck injector from contaminated fuel. After that, Id check injector pump. That said, Ive never had a pump behave as you describe. As I said, the injector issue I mention did create unbelievable havoc, (vibration and noise). And in many years thats the only time Ive had an injector issue with such an extreme noise/vibration. To be clear.
Bulldog04! said:
I’m sure it’s been asked or talked about. I have a 1994 6.5 turbo that was a good running driving power train doner put it in another rig when it was out put new bearings in the bottom end and put together other pickup. Started it and it has a heck of a vibration kinda like miss fire but vibrates the dash and all I’ve cracked 6 out of 8 injectors and have fuel. Pmd is relocated etc. like I said it was a good running power train outside of getting new bearings. I’m at a loss what to look for the other two injectors are right behind the turbo is why I haven’t bled them but any help would be great
Click to expand...
 
The same motor and transmission but were separated a new flex plate and gaskets installed with bearing and put in other pickup.6 out of eight the easy ones to get to made it stutter I need to open the last too gonna make a tool to get to them easy but kinda at a loss. The passenger side does have a sensor at the rear of the head that’s not hooked up to any electrical not sure if that’s important but I did switch pads no change.
dbrannon79 said:
Verify the harmonic balancer is in good condition, they are engine killers and like to snap crankshafts. also the flexplate too. was there anything pulled apart or loosened on the engine during the transplant like the IP or timing components. These engines are externally balanced.

if the HB is good and timing wasn't messed with, then I would install a clear hose on the IP return to check for air in the fuel. also make sure you have good pressure from the lift pump. check all 8 injectors for fuel like said above.

did you keep the same ECM with the transplant? maybe there is something with that too depending on what the engine came out of.
Click to expand...
balancer is good. Nothing else was loosened ecm came from doner as well. I will check the pump pressure and get a tool made to crack the two injectors behind the turbo and check return fuel appreciate the info stay tuned
 
NorthFL1062 said:
Ive owned these since 1984...and still own a 98 K2500 Suburban and a 1994 K1500 Blazer Z71 with 6.5. Im no authority own these engines. I have learned a little. They are simple and dependable. I would look for the simple problem. In your case 1. Replace PCM AND check connections. 2. Check for a stuck injector....any bad fuel you know of? I bought a new engine years ago because to me and a diesel shop it sounded like a rod was loose...or worse. It was a stuck injector from contaminated fuel. After that, Id check injector pump. That said, Ive never had a pump behave as you describe. As I said, the injector issue I mention did create unbelievable havoc, (vibration and noise). And in many years thats the only time Ive had an injector issue with such an extreme noise/vibration. To be clear.
Click to expand...
Fuel was fresh. Took the tank down and got rid of old fuel. New sending unit all new hose front to back the pcm I took from the doner only injectors not checked is the two behind turbo. Need to make a tool and I swapped out the pmd to verify it was good and it still acts the same. Was your noise from idle all three rev like an extreme balance vibration from torque converter? I’m at a loss almost got a few things to go over yet. You happen to know on 94 there’s a sensor passenger side back of the head 2 prong what’s it for
 
Pictures and or videos help a ton.
Temp sensor in the rear of the head can make starting harder in really cold situations but if you plug in the block heater it will overcome that issue easily.

You could chase this for a long time trying to reinvent the wheel of diagnostics.
We kinda jumped around here because the checks already done in the last & its hard to see the whole picture.

Or follow what the GM engineers learned in the 80’s. Codes- yeah they help a ton! Haha. Make sure air filter isn’t blocked & Check for fuel flow out the ip with clear tubing. Once that is ok, crack the lines free of the injectors and see that fuel is coming out, it will be a minuscule amount. Next is compression test.

There is a functional test to shave time between these two. Remove all 8 glowplugs, unplug harness feeding glow plug controller. Have someone crank engine while you watch under the hood. You should see a mist of fuel shoot out each glow plug hole. It won’t make an instant mess or explode, but definitely no open flames and safety specs are not a bad idea here. Fuel vs no fuel out injection lines/injectors is a key point. That mist out the hole would show up individual bad injectors like @NorthFL1062 mentioned can occur (welcome btw- please start a thread about your goodies.).
Then unplugging the fso and running a dry compression test, writing doen the numbers. This part doesn’t just do diagnostics for today, but is valuable information to track health of the engine as time goes on because say in 10 months of use oil consumption is high, a misfire develops worse, etc. knowing compression from day 1 then later when things go goofy- it seriously Helps diagnostics snd can tell wether bandaids vs rebuilds are appropriate 4-5 years later.
 
You must log in or register to reply here.
Back
Top